CHICAGO (Reuters) - Oh, it brings such blessed relief and
now scientists can tell you why -- scratching an itch
temporarily shuts off areas in the brain linked with unpleasant
feelings and memories.

"Our study shows for the first time how scratching may
relieve itch," Dr. Gil Yosipovitch, a dermatologist at Wake
Forest University Baptist Medical Center in Winston-Salem,
North Carolina, said in a statement.

Prior studies have shown that pain, including vigorous
scratching, inhibit the need to itch. Yosipovitch and
colleagues looked at what goes on in the brain when a person is
scratched.

He and colleagues used a technique known as functional
magnetic resonance imaging to see which areas of the brain are
active during scratching. They scratched 13 healthy people with
a soft brush on the lower leg on and off in 30-second intervals
for a total of five minutes.